I'm handing this over to the Pros :)

Have these rocks been painted once already? Or are they manufactured? They don't look quite like real rocks.

I was going to say the same thing. they look 'off'. Anything will be an improvement. I would advocate refacing them with anything else. if you can't do that, then and off-white color is really all you can do with those bold paint colors. Or I suppose you could do a black. but I don't really like either option.

I would save my money and have the entire stone replaced.

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this white quartzite would look good with what you have

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two tones of purple, white mantel, some other white trim and now gray? that is a lot. Im sorry, but those stones are just ugly! There really isn't a lot you can do to make them look better. try a darker gray. if you don't like it, try another color. But seriously save up the money to cover them. plenty of how to videos on "how to reface stone fireplace". It's not that difficult. And quite frankly, you couldn't do much to make it look worse!

also, take off that mantel. It doesn't go. It's too short and too 'country'. Also it might be a good idea to take off the fireplace screen and spray paint it with heat resistant matte black paint. what does it look like on the bottom part?

It's actually quite time consuming to paint those. If you really want to reface, then maybe hold off until you can?? Or, if you really don't mind the extra effort, go ahead and paint them. Maybe start w/just the bottom and try the cream or white,,if you don't like it, try the gray, if you don't like that, try the darker gray or black.

I mean what is the flooring around look like?

I think the stones could work, as they are, but not with your paint choices. And I don't know that stone really works at all with the paint choices you have. So even if you paint the stone, it still may not give you the look you are seeking - plus you would alter the stone surface. I think building some sort of façade around the stone, and/or refacing as Beth H suggested, might be a good option for you.

Yash - I see the pile to know what you were aiming for - cottage and sweet.

White will be cottagey and work but it won't be great. the right shade of gray will work in a sophisticated cottage way, give you contrast to your white trims and help add back some modernity. Usually advocate not painting but you have made a serious commitment to a palette we need to carry somewhere forward.

Some terrific grays . . SW has Light French Gray . . it is a terrific neutral in that zone. http://www.sherwin-williams.com/homeowners/color/find-and-explore-colors/paint-colors-by-family/SW0055-light-french-gray/#/0055/?s=details&p=PS0 It won't overwhelm the space.

Do you mind if I suggest a simple shift? Your wainscot tone is a bit bright for what you want to accomplish . . a gray purple toned blue is bm nickel .. try just one coat to tone down what you have. The pink is great in accessories and that sofa print. Consider a hot pink rug instead for a pop of fun. And pull the 'flowers' into girly glass vases.

https://www.benjaminmoore.com/en-us/color-overview/find-your-color/color/2119-50/nickel?

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The rustic look of the stones does not suit the rest of the room. If removing it is daunting, drywall over the stone.

You can stain or paint the faux stones. Remove the fake mantle.

STAIN

Paint all the stones in the same off white as the top wall section.

Yash, if it feels like it has a plastic type feeling to it, or you can scrape off whatever finish is on there, make sure you use a primer first. And the all white one Bev posted looks good. that might work well on yours